DNA links between Polynesians and South American Indians

DNA has proven a genetic link between Polynesia and South America, but who did the long distance voyaging? A study suggests that people from South America sailed to Rapa Nui (Easter Island) and back, but local historian Scott Hamilton suggests Polynesians are more likely to have sailed to South America and back.

New Scientist: Polynesians and Native Americans met 800 years ago after epic voyage

Polynesians and Native Americans met and had children together around AD 1200, according to a study of modern Polynesian peoples’ DNA. But the encounter didn’t take place on Rapa Nui (Easter Island), the island closest to South America, as has long been suggested. Instead, the Polynesians in question were from islands hundreds of kilometres further away.

The Pacific islands of Polynesia were some of the last places to be settled by humans. Beginning about 5000 years ago, people sailed east from South-East Asia into the Pacific, and found hundreds of islands including Samoa and the Marquesas. The easternmost island, Rapa Nui, was the last to be settled.

This story is supported by genetic, archaeological and linguistic evidence linking Polynesian people with South-East Asians. But some anthropologists have long argued that Polynesians might also have some Native American ancestry, pointing to other factors, such as crops.

“There is the sweet potato in Polynesia, even though it was domesticated in, and is native to, the Americas,” says Alexander Ioannidis at Stanford University in California. It has also been claimed that the famous statues on Rapa Nui resemble ancient Peruvian statues.

Geneticists have found evidence of Native American genes in Polynesian people, but the results are disputed. Now Ioannidis and his colleagues have sequenced the full genomes of 354 Polynesian people from 17 islands, as well as 453 Native Americans from 15 groups from the Pacific coast.

They found small amounts of Native American DNA in Polynesians from the eastern islands: not just Rapa Nui, but also the Palliser islands, the Marquesas and Mangareva. We don’t know exactly which islanders were the point of contact, says the team, but they were almost certainly from one of the more westerly of the group. Later settlers carried the genes to the easterly islands, including Rapa Nui.

The big question now is: who made the journey? Did Polynesians sail east to South America and back, or did Native Americans stray west? Either fits the data, says Ioannidis.

Also from Nature: Native South Americans were early inhabitants of Polynesia

The early peopling of Polynesia attracted worldwide interest in 1947, when the Norwegian explorer Thor Heyerdahl set sail on the Kon-Tiki expedition to test his migration theory. The crew left Peru on a wooden raft, and after 101 days and a voyage of more than 7,000 kilometres, they reached Polynesian shores, thus demonstrating the possibility of early travel from South America to these Pacific islands.

Heyerdahl challenged the scientific community’s view that evidence pointed instead to the peopling of Polynesia by people travelling east from Asia, and his idea that Polynesia was initially populated by South Americans was generally criticized by scholars.

The same scientific community nevertheless discussed cultural contacts between the two regions, because a South American plant, the sweet potato, has a long history of cultivation in eastern Polynesia. The idea that Polynesians voyaged to South America and introduced the plant on their return to Polynesia became the accepted explanation for this.

The DNA evidence.

A key discovery came from their analysis of people from Rapa Nui — a signature could be assigned to Native South American populations from northern coastal regions of South America, and this component was independent of other large historical, or more-recent, admixture events.

A surprising finding is that this signal was also identified in other eastern Polynesian populations, for example in populations in Mangareva, in North Marquesas and South Marquesas, and in Palliser in the Tuamotu Islands.

Figure 1

These other islands lie farther from South America than does Rapa Nui, although for people sailing from South America they are destinations that would be aided by favourable trade winds and currents.

The authors made the notable discovery that an initial admixture event between Native South Americans and Polynesians took place in eastern islands of Polynesia around AD 1150–1230. The exception to this South American admixture timeframe is Rapa Nui, which had a later admixture, dated to around AD 1380.

The earliest genetic signal of Native Southern Americans found by the authors in Polynesia was from people of the Southern Marquesas islands, and the authors argue that Colombians mixed with Polynesians there around AD 1150. This date is so early that it could even suggest South Americans reached there before Polynesians arrived, which would make Heyerdahl partly right if it were the case that South Americans first settled at least the area of eastern Polynesia that has signs of early admixture.

The authors also raise other possible contact scenarios: for example, that Polynesian populations made voyages to South America and then returned to Polynesia along with South American people, or that people returned to Polynesia who carried Native South American genetic heritage. Ioannidis et al. suggest that further genetic studies will be needed to address such alternative hypotheses.

Scott Hamilton supports the latter. Via twitter:

Heyerdahl claimed Polynesians came from the Americas, that they were ‘Red Indians in the Pacific’. An array of evidence shows that Polynesia was settled from the west rather than the east. But tantalising evidence of some Polynesian-American contacts persists.

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Researchers like NZ’s Lisa Matisoo-Smith have found Polynesian chicken bones in Chile. The kumara is South American. Coastal American peoples like the Mapuche & the Chumash have Polynesian-style aquatechnology & words to match. Now DNA evidence of a link’s turned up.

New Scientist magazine has reported on DNA testing done by a group of Mexican researchers. The tests found a small but significant amount of indigenous American DNA in Eastern Polynesian peoples. But the researchers & New Scientist seem to me to misinterpret their data.

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Without any explanation of their reasoning, the DNA scientists & New Scientist’s journalists claim that the new data proves that indigenous Americans sailed to Polynesia. It seems to me vastly more likely that Polynesians reached the Americas, & returned with Americans.

The reed boats South American peoples used on Lake Titicaca & other relatively gentle areas of water seem unsuited to the Pacific. & there is no trace of the influence of American aquatechnology on Polynesian cultures. By contast, Polynesian sewn plank canoes were Americanised.

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It seems to me that the genetic scientists are unaware of the research that Matisoo-Smith & others have amassed about Polynesian journeys to the Americas. DNA data is fascinating; but it still needs careful, historically informed interpretation. This book’s a place to start.

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As with just about all science, this is a work in progress.

 

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4 Comments

  1. Ray

     /  11th July 2020

    You would think the proven spread of the Polynesians across the Pacific Ocean would obviously trump Americans coming the other way. Of course there is a chance it was that way but the DNA seems to suggest it was at the time when the Polynesians were at there high point of long range exploration.

    There seems to have been a number of “explanations ” by various non Polynesians why what they did must have been done by someone else earlier or was just random.
    Same thing about the spread of sweet potatoes, done by early European explorers, or they floated, unfortunately the DNA suggests otherwise but you have to read to the end of this story to hear that!

    Reply
    • Duker

       /  11th July 2020

      Yes..from the link
      “The leaves of sweet potatoes that Captain Cook’s crew collected in Polynesia are stored in the museum’s cabinets. The researchers cut bits of the leaves and extracted DNA from them.
      The Polynesian sweet potatoes turned out to be genetically unusual — “very different from anything else,” Mr. Muñoz-Rodríguez said.
      The sweet potatoes found in Polynesia split off over 111,000 years ago from all other sweet potatoes the researchers studied.”

      I trust the ancient DNA of plants more than modern DNA of humans and then trying to extract by computer models a hit to people in South America again with modern DNA

      Reply
  2. Duker

     /  11th July 2020

    The sampling of modern DNA from existing populations of both Polynesia ( ‘flitering out’ the european) and South America and then after statistical and computer modelling of the results to prove something from 800-1000 yrs ago just wont work.
    The modern DNA analysis really only allows you to go back 400 years or so. People get all sorts of crazy results ( for small % ) when they do those ancestry DNA tests now. Maybe 1900 was a good time to test, but the movements of people for 2020 era is so much bigger.

    if they had ancient DNA from say 700 years ago in NZ or Rapa Nui and compared to ancient South American DNA which is older and found a link, maybe they could say they had something. Thats not what they did. As well how do you exclude the original origins of both Polynesians and South Americans from Asia around 10K years back

    The Incas were a elite mountain people, origin in the city state of Cusco in Peru around 1200AD who controlled large swathes (15k to 40k people ruling 10 mill) but didnt intermarry so much, in some ways similar to early Roman empire but a for shorter period.
    Their level of technology was similar to Polynesians. No writing, no wheels, or draught animals to haul or ride. No iron or steel or money or system of markets.

    Reply
  3. Patzcuaro

     /  11th July 2020

    Perhaps they should be checking for Greek DNA.

    “The man who gifted the Captain Hamilton statue to the city is now peddling claims ancient Greeks settled in New Zealand before Māori – a view dismissed by scholars as wacky and ‘racist nonsense’.”

    https://www.stuff.co.nz/national/politics/122078046/sir-william-gallaghers-wacky-history-claims-embolden-racists

    Reply

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